Will the PCI Express 2.0 x16 video card fit in a PCI Express x16 slot?

Yes, they are backward compatible. If you had a PCI-Express 2.0 slot it would run slightly faster as it allows more bandwidth to travel through. The difference is negligible though.|||yes they make the cards forward compatible meaning that it will still work but not as well. But with the current cards they dont utilize the PCI-e 2.0 fully so you wont notice any difference